maybe I missed some cool early 80s stuff but personally I think that Satriani was as much of a revelation to guitar music as Hendrix. Try satch tracks like Echo, Hordes of Locusts and The Forgotten and tell me Hendrix was better. I'll laugh but you won't hear me.
Lots of the people who say X was the greatest were young when they met their music and associate it with discovering how cool music can be. As for me, my fave guitarist might well be Alex Lifeson from Rush, check out La Villa Strangiato, so much tragedy, so much soul, such a great dearth of stiltonesque miasma (AKA cheese), such tone, such blinding technique. How old was I when i first heard lifeson? 6. Now I'm 24 and I'm stuck in my old ways.